PTP pNPP Assay: PTP activity was assayed using p-nitrophenyl phosphate (pNPP) as a substrate in DMG buffer (50 mM DMG, pH 7.0, 1 mM EDTA, 150 mM NaCl, 2 mM DTT, 0.1 mg/mL BSA) at 25° C. The assays were performed in 96-well plates. Normally, to determine the IC50 values, the reaction was initiated by the addition of enzyme (final concentration of 10 nM) to a reaction mixture (0.2 mL) containing 2 mM (Km for the substrate) pNPP with various concentrations of inhibitors. The reaction rate was measured using a Spectra Max Plus 384 Microplate Spectrophotometer (Molecular Devices). For compound 10, the final TC-PTP concentration was 0.04 nM. The reactions were incubated at room temperature for 30 min and quenched with 5N NaOH. The absorbance at 405 nm was read on the SpectraMax Plus 384 Microplate Spectrophotometer. For the reversibility test, the enzyme was incubated with the inhibitor at room temperature for 30 min before pNPP was added to initiate the reaction. The reaction was then incubated at room temperature.
Enzyme Kinetic Assay: PTP activity was assayed using p-nitrophenyl phosphate (pNPP) as a substrate in 3,3-dimethylglutarate buffer (50 mM 3,3-dimethylglutarate, pH 7.0, 1 mM EDTA, 150 mM NaCl, 2 mM DTT, 0.1 mg/mL BSA) at 25° C. The assays were performed in 96-well plates. Normally, to determine the IC50 values, the reaction was initiated by the addition of enzyme (final concentration at 10 nM) to a reaction mixture (0.2 mL) containing 2 mM (Km for the substrate) pNPP with various concentrations of inhibitors. The reaction rate was measured using a SpectraMax Plus 384 Microplate Spectrophotometer (Molecular Devices). To determine the mode of inhibition, the reactions were initiated by the addition of PTP-MEG2 to the reaction mixtures (0.2 mL) containing various concentrations of pNPP with different concentrations of the inhibitor 7.
Inhibition of allosterically sensitized mutant form of His6-tagged human FAP1 catalytic domain at 500 nM using pNPP as substrate incubated for 90 mins by quenched phosphatase activity assay
Inhibition of allosterically sensitized mutant form of His6-tagged human FAP1 catalytic domain using pNPP as substrate after 90 mins by quenched phosphatase activity assay
Inhibition of allosterically sensitized mutant form of His6-tagged human FAP1 at 1000 nM using pNPP as substrate by quenched phosphatase activity assay
Inhibition of FAP1 (unknown origin) expressed in Escherichia coli BL21 using p-nitrophenyl phosphate as substrate measured after 30 mins by UV-vis spectrophotometric method